Breastfeeding Linked to Lower Cardiovascular Risk

DENVER — Breastfeeding was linked to lower long-term cardiovascular risk than not breastfeeding, with the effect size greater in those with gestational diabetes, according to a study presented at the Society for Maternal-Fetal Medicine (SMFM) 2025 Annual Pregnancy Meeting.

“These results highlight the importance of breastfeeding for those with prior gestational diabetes, who are less likely to exclusively breastfeed at hospital discharge, are more likely to supplement with formula when breastfeeding, and breastfeed for shorter durations compared with those without gestational diabetes,” said Christine Field, MD. Field, a Maternal-Fetal Medicine Fellow at The Ohio State University College of Medicine in Columbus, Ohio, told attendees, “These results highlight the potential value of postpartum cardiovascular risk assessment that integrates both modifiable behavioral risk factors, such as breastfeeding, and risk-enhancing adverse pregnancy outcomes, such as gestational diabetes.”

“Breastfeeding itself is associated with weight loss, activity, and an increase in metabolism, and therefore it makes sense that it would reduce cardiovascular risk,” Diana S. Wolfe, MD, MPH, the obstetric director of Maternal-Fetal Medicine Cardiology Joint Program and a professor at Montefiore Einstein, told Medscape Medical News. “Further investigation into the biologic plausibility and rationale behind this association could provide treatment for patients with adverse pregnancy outcomes to mitigate the cardiovascular risk.”

But she cautioned about drawing too strong a conclusion about long-term cardiovascular risk from these findings, a point echoed by Melissa Wong, MD, an assistant professor of Obstetrics and Gynecology at Cedars-Sinai in Los Angeles, who, like Wolfe, was not involved in the study.

Wong said that the study adds to our understanding that breastfeeding may be even more protective for those who have gestational diabetes. “But, like many breastfeeding studies, it’s very hard to disentangle the factors that are protective against cardiovascular disease from those that also make breastfeeding more feasible, like socioeconomic status, education, and health literacy.”

Breastfeeding previously has been linked to a multitude of benefits for mothers, including reduced risk for breast cancer, ovarian cancer, high blood pressure, and type 2 diabetes, Field noted. Further, a recent meta-analysis suggested breastfeeding is linked to a reduced risk for cardiovascular disease, including coronary heart disease and stroke.

However, “the relative benefit of breastfeeding for reducing cardiovascular disease may vary in the setting of adverse pregnancy outcomes such as gestational diabetes,” Field said. How gestational diabetes might mediate the association between breastfeeding and cardiovascular risk is what they sought to better understand.

The researchers therefore conducted a secondary analysis of the Hyperglycemia and Adverse Pregnancy Outcome (HAPO) Follow-Up Study conducted between February 2013 and 2016 across 10 of 15 sites. Though the original HAPO study investigated abnormal blood glucose during pregnancy and adverse pregnancy outcomes, the follow-up study looked at the longer-term cardiometabolic health of the mothers and their offspring. The study included only women delivering at full term who did not have pregestational diabetes.

Mothers completed questionnaires after their pregnancy regarding whether they breastfed. Then, 10-14 years after delivery, researchers looked at a composite of fatal and nonfatal coronary heart disease and stroke in the mothers and their 10-year and 30-year risk of developing cardiovascular disease based on the Framingham Risk Score.

Field’s group then looked at who had gestational diabetes in their pregnancy during the original HAPO study, diagnosed with a 2-hour, 75-g oral glucose tolerance test at 28 weeks. The researchers adjusted their analysis for the site, the time from delivery to follow-up, and the mothers’ parity, age, body mass index (BMI), height, and alcohol and tobacco use.

The 4540 mothers were a median 30 years old and had a median BMI of 26.6. A significantly higher proportion of mothers who did not breastfeed used tobacco (12.5%) than those who did breastfeed (3.2%).

Women who breastfed had lower estimated 10-year and 30-year cardiovascular risks than those who didn’t breastfeed. Based on a comparison of the least-square means of estimated risk, those who breastfed had an adjusted beta coefficient 0.13 lower for 10-year risk and 0.36 lower for 30-year risk, which “translates into an approximately 5% reduction in estimated cardiovascular risk with breastfeeding across the whole study population,” Field said.

Including gestational diabetes status in the analysis revealed that it had a significant impact on cardiovascular risk.

“Among those who breastfed, individuals with gestational diabetes lowered their 10-year and 30-year cardiovascular risk to a greater extent than those who did not have gestational diabetes,” Field said. Among breastfeeding moms, the adjusted beta coefficient was −0.09 in those without gestational diabetes and −0.52 in those with gestational diabetes for the 10-year estimated risk. For 30-year risk, the beta coefficient was −0.25 in those without and −1.33 in those with gestational diabetes.

“These beta coefficients translate into an approximately 15% reduction in estimated cardiovascular risk with breastfeeding among those with gestational diabetes,” Field said.

The study was limited by a lack of data on how long the mothers breastfed and whether they exclusively breastfed or supplemented with formula, Field said. The study also excluded women who may have even greater risks of not breastfeeding and of cardiovascular disease since those with a preterm birth and those with pregestational diabetes were not involved.

Finally, because of blinding in the original study, mothers with gestational diabetes did not receive treatment for it, so the “extent [to which] management of gestational diabetes impacts breastfeeding and future cardiovascular risk requires further study,” Field said.

“Patient education and support, such as via community health workers and patient-centered programs, can facilitate the ability for postpartum patients to have the opportunity and time to breastfeed,” Wolfe said.

The research was funded by the National Institute of Diabetes and Digestive and Kidney Diseases. Field, Wolfe, and Wong had no disclosures.

Tara Haelle is a health and science journalist based in Dallas.